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| United States Patent |
6,119,558
|
|
Foley, Jr.
|
September 19, 2000
|
Manual pipe tong having secondary safety latch
Abstract
Manual pipe tong comprising secondary latch. The pipe tong comprises a
handle and a plurality of linked jaw segments pivotally attached to the
handle. Two of the segments are first and second latch segments, and are
releasably engageable to form a primary latch. The primary latch may be
released and the jaw segments opened to encircle a tubular for makeup of a
threaded connection. The first latch segment comprises substantially
parallel upper and lower surfaces, and projections on each of those
surfaces. A hooking member on the second latch segment comprises a pair of
spaced-apart hooks joined by a handle, and is rotably disposed on the
second latch segment so that the hooks sandwich the second latch segment.
The hooking member is rotatable between first and second positions, and in
the second position the hooks engage the projections on the first latch
segment so as to form a secondary safety latch. In the event of a tong jaw
segment failure, the secondary safety latch keeps the jaw segment
fragments linked to the unbroken jaw segments, preventing projectiles from
being formed by the fragments. The secondary safety latch also prevents
unintentional unlatching of the primary latch.
| Inventors:
|
Foley, Jr.; Lawrence E. (203 Beau Pre Rd., Lafayette, LA 70508)
|
| Appl. No.:
|
296095 |
| Filed:
|
April 21, 1999 |
| Current U.S. Class: |
81/90.5; 81/90.7 |
| Intern'l Class: |
B25B 013/00 |
| Field of Search: |
81/90.3-90.9
|
References Cited
U.S. Patent Documents
| 1334250 | Mar., 1920 | Langford | 81/90.
|
| 2093788 | Sep., 1937 | Vaughn | 81/90.
|
Primary Examiner: Smith; James G.
Assistant Examiner: Thomas; David B.
Attorney, Agent or Firm: Lambert; Jesse D.
Claims
I claim:
1. A manual pipe tong, comprising:
a) a handle;
b) a plurality of linked jaw segments pivotally connected to said handle,
two of said jaw segments comprising first and second latch segments, said
first and second latch segments releasably engageable with one another to
form a primary latch, permitting said jaw segments to be opened to engage
a tubular within said jaw segments and said first and second latch
segments thereafter engaged so that said jaw segments encircle said
tubular; and
c) a secondary latch, comprising:
i) at least one hook engaging surface on said first latch segment, and
ii) a hooking member rotatably disposed on said second latch segment, said
hooking member rotatable between first and second positions,
whereby when said first and second latch segments are engaged to form said
primary latch, said hooking member in said first position does not engage
said at least one hook engaging surface, and said hooking member in said
second position engages said at least one hook engaging surface so as to
at least partially encircle said at least one hook engaging surface and
thereby link together said first and second latch segments independent of
said primary latch.
2. An improved manual pipe tong having both primary and secondary latches,
comprising:
a) a handle and a plurality of linked jaw segments pivotally connected to
said handle, two of said jaw segments comprising first and second latch
segments, said first and second latch segments configured to releasably
engage one another to form a primary latch, said first latch segment
further comprising a hook engaging surface, said jaw segments when latched
adapted to engage a tubular member to permit applying torque to a threaded
connection; and
b) a hooking member rotatably disposed on said second latch segment and
comprising at least one hook and a handle, said hooking member rotatable
between a first position wherein said at least one hook does not engage
said hook engaging surface of said first latch segment and a second
position wherein said at least one hook engages and at least partially
encircles said hook engaging surface of said first latch segment and forms
a secondary latch, said secondary latch adapted to link together said
first and second latch segments independent of said primary latch and to
prevent disengagement of said primary latch should a tong jaw segment
fail.
3. The tong of claim 2, wherein said at least one hook further comprises an
end cap covering said at least one hook.
4. A manual pipe tong, comprising:
a) a handle;
b) a plurality of linked jaw segments pivotally connected to said handle,
two of said jaw segments comprising first and second latch segments, said
first latch segment comprising upper and lower surfaces, said first and
second latch segments releasably engageable with one another to form a
primary latch, permitting said jaw segments to be opened to engage a
tubular within said jaw segments and said first and second latch segments
thereafter engaged so that said jaw segments encircle said tubular; and
c) a secondary latch, comprising:
i) a hook engaging surface comprising a projection extending outwardly from
each of said upper and lower surfaces of said first latch segment
ii) a hooking member rotatably disposed on said second latch segment, said
hooking member comprising a pair of opposed, spaced apart hooks
sandwiching said second latch segment and joined by a handle, said hooks
adapted to releasably engage said projections, said hooking member
rotatable between first and second positions,
whereby when said first and second latch segments are engaged to form said
primary latch, said hooking member in said first position does not engage
said hook engaging surface, and said hooking member in said second
position engages said hook engaging surface so as to at least partially
encircle said hook engaging surface.
5. The tong of claim 4, further comprising a spring disposed between said
hooking member and said second latch segment, said hooking member biased
toward said second position by said spring.
6. The tong of claim 5, wherein said projections have an undercut cross
section, and said hooks have a bevel adapted to matingly engage said
undercut cross section.
Description
BACKGROUND
1. Field of the Invention
This invention relates to an improved apparatus for making up threaded
tubular connections. More specifically, the present invention relates to a
manual pipe tong having a handle and jaws connected thereto, and
comprising a secondary safety latch which, in the event of a tong failure
due to fracturing of the tong jaw segments, keeps the fractured pieces of
the tong jaw segments connected together, thereby preventing the pieces
from flying outward and potentially injuring workers. The improved tong of
the present invention also prevents unintentional opening of the tong
jaws, which may occur due to a failure of the tong line.
2. Related Art
Threaded connections are used to join lengths of tubulars in many different
applications. Although the ensuing description addresses primarily the use
of such tubulars (commonly known as "drill pipe") in the drilling of earth
boreholes, such as for oil and gas wells, it is understood that the scope
of the present invention encompasses manual tongs used to make up threaded
connections on tubulars in any application.
Each section or "joint" of drill pipe typically has an upset at each end,
one end comprising a pin connection and the other a box connection. This
upset section, commonly referred to as a "tool joint", provides a larger
diameter surface which may be readily engaged by pipe tongs, as will be
described below.
Manual pipe tongs typically comprise several linked-together and
articulated jaw segments (sometimes collectively referred to as "jaws"),
the jaw segments pivotally connected to an extended handle, which, as the
ensuing description will show, creates a lever for the application of
torque to the threaded connection. At least some of the jaw segments
contain dies, which are hardened teeth to grip the surface of the tubular
to be tightened, such as the tool joints of the drill pipe. The jaws
include at least two segments, comprising first and second latch segments,
which form a primary latch which permits the jaws to be opened, encircled
about a tubular, then latched closed by engaging the first latch segment
with a mating part of the second latch segment. Once the jaws are closed
about the tool joint, the drill pipe connection is then "made up" by
pulling on the handle (which provides greatly increased leverage, as the
pull point is displaced several feet from the axis of rotation), usually
by a cable or chain connected to a cat head on the rig drawworks, which
can provide tremendous pulling force. This operation is reversed to
unscrew or "breakout" the threaded connection. The torque required to make
up and breakout drill pipe connections is quite high, and consequently the
pulling force on the tongs is high, with resulting great stress on the
various components of the tong, and in particular the jaw segments.
A large percentage of the major accidents which occur on a drilling rig
floor involve failure of the drill pipe tongs, when such tongs are
subjected to great stress. A typical occurrence is a catastrophic failure
by fracture of a jaw segment, with the result that the tong jaws fly open,
come unlatched, and the unlatched and thereby free-flying fragment or
fragments thus created (which may weigh, for example, 40 to 160 pounds)
flies outward with tremendous force. Any rig worker in the path of such
projectile would certainly be injured, and perhaps killed. Catastrophic
failures of this nature are minimized by careful design and testing of the
pipe tong components before use. In addition to testing, it is further
desirable to link together any fragments of the jaw segments created by a
failure of one or more jaw segments, so that such fragments remain
connected to the pipe tong and cannot fly any great distance away, thereby
greatly reducing or eliminating injury and death due to such projectiles.
Some additional number of accidents occur when pipe tong jaws come
unlatched when under stress, the pipe tongs then suddenly swinging around
under influence of the pulling force and striking a worker. Such
unlatching may be caused by a failure of the line pulling the tong. It is
therefore further desirable to provide a means to prevent unintentional
and undesired unlatching of the pipe tongs.
SUMMARY OF THE PREFERRED EMBODIMENT OF THE PRESENT INVENTION
The present invention comprises an improved manual pipe tong, comprising a
secondary safety latch which links together the tong jaw segments so that
even in the event of a jaw segment failure, the jaw segment fragments
remain connected to the pipe tong. The secondary safety latch also
prevents unintentional opening of the jaw latch.
The improved manual pipe tong of the present invention comprises a handle
with jaws connected thereto, the jaws comprising a plurality of
linked-together segments which are pivotally connected to the handle. Two
of the jaw segments are not pinned to one another, but comprise first and
second latch segments having mating shapes which together form a primary
latch which may be opened to permit the jaws to be placed about a tubular.
The present invention further comprises a secondary latch, wherein the
first latch segment comprises upper and lower surfaces and an
outwardly-extending projection on each of the upper and lower surfaces.
The second latch segment comprises a hooking member pivotally attached
thereto, which includes a pair of opposed, spaced-apart hooks joined by a
handle. The hooks are disposed adjacent the upper and lower surfaces of
the second latch segment, thereby sandwiching the second latch segment
therebetween. When the primary latch is engaged by engagement of the first
and second latch segments, the secondary safety latch may be engaged by
pivoting the hooking member on the second latch segment, so as to engage
the hooks about the projections of the first latch segment. With the
secondary safety latch thus engaged, any fragments resulting from failure
of jaw segments remain linked to other jaw segments and ultimately to the
tong handle, and are thus prevented from flying outward. Further, the
secondary latch keeps the primary latch from unintentional opening.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a prior art manual pipe tong engaged about
a tubular.
FIG. 2 is a top view of a prior art manual pipe tong.
FIG. 3 is a top view of the improved manual pipe tong of the present
invention.
FIG. 4 is a perspective view of the hooking member of the secondary latch.
FIG. 4a is a side view of the hooking member of the secondary latch, more
clearly showing the spring.
FIG. 5 is a top view of the present invention, showing the primary latch
engaged, with the secondary latch unengaged.
FIG. 6 is a top view of the present invention, showing both the primary and
secondary latches disengaged and the latch segments rotated apart.
FIGS. 7 and 7a are cross sections along section A-A'.
FIG. 8 is a view of the apparatus showing tong jaw fragments retained by
the secondary latch of the present invention.
FIG. 9 is a view of another embodiment of the hooking member.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT
The presently preferred embodiment of the present invention comprises an
improved manual pipe tong comprising a primary latch and a secondary
safety latch. Although the ensuing description contains certain
specificities related to presently preferred embodiments of the invention,
it is understood that the scope of the invention is not limited thereby,
but encompasses all manual pipe tongs having both primary and secondary
latches, wherein the secondary latch serves to maintain any fragments of
the tong jaws in linked-together relation with the tong handle in the
event of a tong jaw failure and prevents unintentional opening of the tong
jaws. The scope of the appended claims likewise covers all embodiments of
such manual pipe tongs.
FIG. 1 shows a prior art manual pipe tong. The pipe tong 10 comprises a
handle 20 and jaws 30, the jaws 30 comprising several linked together
segments, enumerated jaw segments 30a, 30b, and first and second latch
segments 30c and 30d, respectively. It is to be noted that although a
total of four jaw segments are illustrated herein, the particular number
of jaw segments is not critical, but rather illustrative only. Jaws 30 are
pivotally connected to handle 20. First latch segment 30d engages second
latch segment 30c, forming a primary latch 40. Second latch segment 30d
may be rotated out of engagement with first latch segment 30c, permitting
jaws 30 to be opened up, a tubular 50 to be engaged within jaws 30, and
first and second latch segments 30c and 30d thereafter engaged to close
and encircle the jaws around the tubular. By pulling on handle 20 (denoted
by the arrow A), usually by means of a cable or chain connected to a
drilling or workover rig drawworks or the like, jaws 30 tighten about
tubular 50 and torque may be applied to the connection through the lever
aspect of handle 20.
FIG. 2 is a top view of the prior art manual pipe tong, tubular 50 omitted
for clarity. Like elements have like reference numbers.
FIG. 3 shows a top view of the presently preferred embodiment of the
improved manual pipe tong of the present invention, showing secondary
safety latch comprising a hooking member 60 having hooks 90a and 90b (90b
not shown) pivotally attached to second latch segment 30d, and a plurality
of hook engaging surfaces, which in the preferred embodiment comprise
projections 70a and 70b (70b not shown) on first latch segment 30c,
hereafter discussed in detail. In FIG. 3, both primary latch 40 (formed by
engagement of first and second latch segments 30c and 30d) and secondary
latch (formed by engagement of hooks 90a and 90b with projections 70a and
70b) are engaged. In FIG. 3, hooking member 60 is in a first position. In
the preferred embodiment, a spring 95 (shown in more detail in FIG. 4a) is
disposed between hooking member 60 and second latch segment 30d, spring 95
biasing hooking member 60 toward the first position. Although a coil
spring is shown in FIG. 4a, which encircles pin 91 and bears against
hooking member 60 and second latch segment 30d, it is understood that
other configurations of springs could be used, such as a compression
spring.
Handle 20 and jaws 30 of the present invention are typically made of a
forged or cast metal, such as cast steel. However, other materials may be
used, such as other metals or metal alloys, or other materials providing
the required strength.
Referring to FIG. 4, the presently preferred embodiment of hooking member
60 is shown in perspective. Hooking member 60 comprises a handle 80
joining a pair of spaced-apart, opposed hooks 90a and 90b. Hooking member
60 is rotatably attached to second latch segment 30d by pin 91, or other
like means inserted through holes 90c, thereby forming a pivot point about
which hooking member 60 may rotate. Hooking member 60 may be made of
various suitable materials well known in the art, including metal alloys
and the like. Hooking member 60 is dimensioned so as to adapt to
installation on second latch segment 30d, with hook 90a adjacent an upper
surface of second latch segment 30d and hook 90b adjacent a lower surface
of second latch segment 30d. The size, shape and configuration of hooks
90a and 90b may be adapted for advantageous engagement of projections 70a
and 70b. FIG. 4a is another view of hooking member 60, showing pin 91
engaged therethrough, and spring 95 encircling pin 91, so that spring 91
can bear against hooking member 60 and second latch segment 30d. Hooking
member 60 may be formed from metal, metal alloy, or other suitable
materials well known in the art, with the different parts joined by
welding, or by casting or forging hooking member in one piece.
FIGS. 3, 5 and 6 show the pipe tong of the present invention in different
stages of latching. In FIG. 3, as described above, primary latch 40 is
engaged, and hooks 90a and 90b and hooking member 60 are in a first
position, engaging projections 70a and 70b and forming the secondary latch
of the present invention. In FIG. 5, hooking member 60 is rotated to a
second position, disengaging hooks 90a and 90b (90b not shown) from
projections 70a and 70b (70b not shown). Primary latch 40 is still
engaged.
In FIG. 6, second latch segment 30d is rotated out of engagement with first
latch segment 30c, and hooking member 60 is rotated back to its first
position. In the position shown in FIG. 6, both the primary latch 40 and
secondary latch are disengaged, and jaws 30 may then be placed in position
to receive a tubular.
In the preferred embodiment, the size, configuration and shape of first and
second latch segments 30c and 30d, hooks 90a and 90b, and the placement of
pivotal mounting point of hooking member 60 may permit the secondary
safety latch of the present invention, formed by engagement of hooks 90a
and 90b with projections 70a and 70b, to latch by rotation of second latch
segment 30d into its final latched position. That is to say, in that
embodiment, hooking member 60 need not be manually rotated to its second
position, but rather hooking member 60 (under the bias of spring 95) is
pushed out of its first position by contact with projections 70a and 70b;
into its second position by continued rotation of second latch segment 30d
into the primary latch position; then once second latch segment 30d is
fully rotated into position against first latch segment 30c and primary
latch 40 is formed, hooking member is biased by spring 95 and "snaps into"
its first position, as shown in FIG. 3, forming the secondary latch.
FIGS. 7 and 7a show two different embodiments of first latch segment 30c,
along cross section A-A' from FIG. 6. Referring to FIG. 7, first latch
segment 30c comprises upper and lower surfaces and comprising an upper
projection 70a and a like, opposing lower projection 70b, for engagement
with hooks 90a and 90b of hooking member 60. Upper and lower projections
70a and 70b may be formed in various ways: by casting into first latch
segment 30c when first latch segment 30c is formed; by milling, machining
or otherwise removing material from the upper and lower surfaces of first
latch segment 30c to leave upper and lower projections 70a and 70b; or by
adding projections by welding, bolting, or other like means well known in
the art. The shapes of upper and lower projections 70a and 70b are
configured so as to cooperatively engage hooks 90a and 90b of hooking
member 60 and form a secure connection point. FIG. 7a shows an alternative
embodiment of projections 70a and 70b, and hooks 90a and 90b. In that
embodiment, upper and lower projections 70a and 70b have an undercut
profile, wherein a width of the projections increases in a direction away
from the body of first latch segment 30c. Hooks 90a and 90b of hooking
member 60, also shown in cross section in FIG. 7a, have angled surfaces
90d and 90e, respectively, configured to engage mating undercut profiles
of upper and lower projections 70a and 70b, thereby tending to force hooks
90a and 90b into tighter engagement with upper and lower projections 70a
and 70b when force is applied.
To use the apparatus of the present invention, starting from the position
shown in FIG. 6, jaws 30 are opened sufficiently to accept a tubular 50.
First and second latch segments 30c and 30d are swung together to form
primary latch 40, as shown in FIG. 5. Hooking member 60 is first pushed
out of its first position to its second position, then under the bias of
spring 95 pushed into its first position and the tong fully latched about
tubular 50, as shown in FIG. 3 (tubular 50 omitted for clarity). To
disengage tong 10, the foregoing procedure is reversed. In the position
shown in FIG. 3, with both the primary latch and secondary safety latch
engaged, first and second latch segments 30c and 30d are prevented from
disengagement, and should a jaw segment fail the secondary safety latch
formed by hooks 90a and 90b of hooking member 60 and projections 70a and
70b maintains the fragments in linked together relationship with the
remaining jaw segments, and ultimately with the tong handle.
FIG. 8 illustrates the function of the secondary safety latch of the
present invention during a failure of a jaw segment. By way of
illustration, second latch segment 30d is shown as fractured, creating
fragments 100a and 100b. Although jaws 30 disengage from tubular 50 (not
shown herein for clarity), it can be seen that the secondary safety latch
keeps fragment 100b linked to the other jaw segments, preventing fragment
100b from becoming a projectile and flying outwardly so as to hurt a
nearby worker. Although second latch segment 30d is shown as the fractured
segment, it is understood that the secondary safety latch effectively
links together all jaw segments so that regardless of which segment
fractures, no fragments may fly away from the tong.
It can be seen from the description and figures that secondary safety latch
comprising hooking member 60 and projections 70a and 70b also prevents
unintentional and unwanted unlatching of first and second latch segments
30c and 30d, as previously described.
Yet another embodiment of hooking member 60 is shown in FIG. 9. That
embodiment comprises end coverings 110 over hooks 90a and 90b, as shown.
End coverings 110 may be formed of separate sheet material (such as sheet
steel or the like) attached to hooks 90a and 90b by welding or other like
means. Alternatively, hooks 90 may be integrally formed by machining
appropriate profiles into sheet iron, leaving stock in place to form end
coverings 110.
Although the description herein contains various particularities and
specificities, these are intended to illustrate some of the presently
preferred embodiments and not limit the scope of the invention. Various
alternative embodiments are possible. For example, different materials may
be used for hooking member 60 and projections 70a and 70b; the shapes of
hooking member 60 and projections 70a and 70b, including the engaging
surfaces, may be altered; and the secondary latch may comprise only a
single hook (for example, hook 90a only) and single mating projection (for
example, projection 70a only). In other embodiments, a linear movement of
the hooking member, rather than a rotational movement, may be used. In
such an embodiment, hooking member 60 would move linearly, engaging and
disengaging from the hook engaging surfaces in a linear fashion.
Therefore, the scope of the invention should be governed not by the
description herein, but by the appended claims and their legal
equivalents.
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